At first, you will have to login into your WordPress Admin area using your WordPress login information and click to Appearance on the left side on the WordPress Admin panel. When you click to Appearance, you will see a dropdown menu and you will see “Theme Options” in the dropdown menu. Please, click on “Theme Options” and you will click “header”. Under the “header”, you will get an option called “Logo Image” to upload your custom logo.
So, the work diagram: WordPress Admin Area > Appearance > Theme Options > header > Logo Image
Thus, you can upload your custom logo through WordPress admin following above mentioned instruction.